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Increase code readability

Rearrange code portions

The end-weight principle for natural languages says the longer stuff should be at the end of a sentence.
In Groovy/Java, while and if statements are usually heavy in the block/statement, and light in the condition.
When the statement/block is short and the condition long, it can be more readable to put the block last.
Eg:

is transformed to:

We could use 'unless' and 'until' if using 'if' and 'while' caused problems.

Common modifier

When a long list of methods and/or fields have the same modifier/s,
it may be more readable to apply them to a whole block, eg:

becomes

Transform statements

Eg:

becomes

triggered by the 'static' modifier of a field in a function.

Names for operators

Use names instead of symbols for operators, eg:

becomes

or change their names to something shorter, eg:

becomes

Equivalence of block and statement

Forgoing curlies for all statements, making a statement and block equivalent always:
Eg:

Use other natural languages with Groovy

Enable fuller internationalization of Groovy, eg:

would convert to

if a Spanish option for Groovy was loaded.

More Seamless Integration with Java and Java-like languages

Embed Java code within Groovy without quoting it,
and without needing to bind variables to the same name, ie, no binding.setVariable('i', i).
eg:

Simplify the Antlr lexer/parser

Many existing syntactic sugars could be re-implemented as macros in a standard macro library.
This might simplify the Antlr lexer/parser, enabling better maintenance of and extensions to it.

Eg, properties where:

expands to:

Other examples:

for( i in ... ) expanding to code using iterator

shorthand notation for invoking method with closure/s at last parameter/s